The PHENIX Forward Silicon Vertex Detector

Abstract

A new silicon detector has been developed to provide the PHENIX experiment with precise charged particle tracking at forward and backward rapidity. The Forward Silicon Vertex Tracker (FVTX) was installed in PHENIX prior to the 2012 run period of the Relativistic Heavy Ion Collider (RHIC). 1 arXiv:1311.3594v2 [physics.ins-det] 14 Feb 2014The FVTX is composed of two annular endcaps, each with four stations of silicon mini-strip sensors, covering a rapidity range of 1.2 < |η| < 2.2 that closely matches the two existing PHENIX muon arms. Each station consists of 48 individual silicon sensors, each of which contains two columns of mini-strips with 75 µm pitch in the radial direction and lengths in the φ direction varying from 3.4 mm at the inner radius to 11.5 mm at the outer radius. The FVTX has approximately 0.54 million strips in each endcap. These are read out with FPHX chips, developed in collaboration with Fermilab, which are wire bonded directly to the mini-strips. The maximum strip occupancy reached in central Au-Au collisions is approximately 2.8%. The precision tracking provided by this device makes the identification of muons from secondary vertices away from the primary event vertex possible. The expected distance of closest approach (DCA) resolution of 200 µm or better for particles with a transverse momentum of 5 GeV/c will allow identification of muons from relatively long-lived particles, such as D and B mesons, through their broader DCA distributions.

Measurement of the relative yields of ψ(2S) to ψ(1S) mesons produced at forward and backward rapidity in Adare1, Aidala2, Ajitanand3 et al. 2017Phys. Rev. CSelf Cite

“…Muons considered in this analysis pass through a the forward vertex tracking detector (FVTX) [27], a hadron absorber with a thickness of ∼ 10 interaction lengths, then through three multi-plane cathode strip tracking chambers which reside in a radial magnetic field. After the tracking chambers are more layers of absorbers and Iarocci tubes for muon identification, where tracks must penetrate at least 2.5 interaction lengths of additional steel absorber.…”

Highlights from PHENIX at RHIC

“…To enhance the capability of heavy flavor measurements via precision tracking, the PHENIX collaboration has installed a silicon vertex tracker both in central rapidity (VTX) and in forward rapidity (FVTX) regions. The VTX [11] and FVTX [12] detectors cover respectively in rapidity | y |< 1.2 and 1.2 < y < 2.2 , and 2π in azimuth acceptance. With these two upgrades, the PHENIX experiment has collected large data samples.…”

Probing the Spin Structure of the Proton Using Polarized Proton-Proton Collisions and the Production of W Bosons

“…For this analysis, the FVTX can provide an important additional layer of precision, because it can help to identify background-events which do not originate from the primary event vertex of a collision [24]. , and readout electronics (green).…”

“…, and readout electronics (green). The FVTX was designed to mount directly onto the Silicon Vertex Detector (center) [24]. This configuration allows for a very high density of interleaved chips, in several layers, covering a maximum area around the beam pipe for detection of secondary vertex events.…”